The first boathouse at The King’s School, Worcester was a barge purchased in 1914 for £18. Three boathouses later, an elegant prow-shaped building by Associated Architects has replaced a 1950s structure on the same site designed by the then master in charge of rowing. Every aspect of the new Michael Baker Boathouse (after an alumni donor) - from its careful siting to the flood-resistant design of the boat store to the meticulous selection of materials - has been lavished with attention to magnificent effect with a vigilant eye to sustainability throughout.

The King’s School, Worcester occupies an organic accretion of buildings which front the southern flank of Worcester Cathedral. The boathouse is Associated Architects’ eighth major intervention at the school over 14 years. Projects include: two 10-year masterplans, a library, and a new sports and performing arts centre, currently on site and due to complete in 2014. The architects’ intimate knowledge of the school and its heritage context is made manifest in the boathouse.

The site is exceptional. Approached through a 2.6m-wide lane which defines the school’s southern boundary, the boathouse sits roughly perpendicular to the Severn River. The cantilevering first floor forms a prow over the embankment, with its parade of handsome horse chestnuts and views of Worcester’s twin landmarks: the cathedral tower and Glover’s Needle, a reminder of the city’s glove-making past.

The brief for the building was simple: a boat store with a multipurpose room above which could accommodate training for rowers as well as school and community receptions. The goal was to create a facility where every King’s pupil would have an opportunity to learn the rudiments of the sport.

Project architect John Christophers brought a strong environmental agenda to the project, having completed Code Level 6/Passivhaus EcoVicarages for the diocese of Worcester (AJ Specification 02.13) and Cobton House, also on the banks of the River Severn, which won an RIBA sustainability award in 2005.

This modest building of just 772m² does what all good buildings should - it makes sense of its surroundings.

By locating an entrance to the upper floor on the axis of Glover’s Needle in the adjacent Creighton Memorial Gardens, the practice has created an approach route through this previously under-utilised part of the school grounds and simultaneously provided wheelchair-friendly access to the building. Its cantilevered prow serves as a landmark on the embankment, anchoring the south-west corner of the campus. The planners were receptive to what Christophers calls ‘a jewel-like modern incident along the embankment.’

The jewel reference is accurate. On the sunny day I visited, the diagonal-laid sweet chestnut cladding shimmered. The 32mm by 25mm chestnut laths of the rainscreen cladding are laid on a 15° angle, ‘like a bias cut dress,’ explains Christophers. The timber prow of the upper floor sits over a brick base which houses the boat store, with a flawlessly crafted ‘belly’ over the door fronting the river. The building’s gentle curve echoes the site boundary which is also Worcester’s Bronze Age fortification line. A rustic brick, chosen to marry with existing Victorian bricks and the local sandstone, is laid in English garden wall bond - three courses of double length stretchers and one course of headers - providing just enough texture to compliment the diagonal siding above.

A handsome timber door from the narrow lane opens onto a dramatic top-lit ice birch-lined stair. On the right, an interior window offers a glimpse into the boat store - which has double the capacity of the old building and is the building’s raison d’être. Christophers refers to the store as ‘sacrificial’: it’s uninsulated, outside the airtightness line and designed to flood. Since the boathouse was occupied last April, the Severn has flooded four times, bringing more than a foot of water into the boathouse without damage.

The immaculate detailing and sensitive choice of materials continues inside. A welcoming maple stair, with 450mm going and 150mm risers, is a marvel, each step carefully aligned with the brick coursing and the beech panelling on either side. Above, a bespoke run of flush rooflights follows the line of the curved wall in an alternating A BB A rhythm, creating a play of shadows on the wall. Motorised for ease of operation, the rooflights open to enable natural ventilation during training, while deep coffers eliminate glare. Triple-glazed windows and sliding doors open to the north overlooking the gardens and cathedral.

The boathouse’s exemplary environmental agenda is simultaneously robust and imperceptible, an approach more practices should adopt. Because the programme required a multipurpose space for training, teaching and receptions, a lightweight responsive building was needed.

Paramount attention was paid to insulation and airtightness with all electrics located in the floor to eliminate penetrations of the airtightness barrier. The project team opted to monitor the building and share data on the CarbonBuzz platform (even though there was no fee to cover this work), a move more practices should consider.

‘An overlooked aspect of sustainability is the need to inspire and delight,’ Christophers told me as we departed. Each summer term, The King’s School, Worcester celebrates its rowers with a black tie dinner and awards evening. It’s hard to imagine a more magical spot for such a festivity than the prow of the boathouse with all doors thrown open overlooking the gardens’ herbaceous borders.

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